Tests and diagnosis

If you have signs and symptoms of acute coronary syndrome, your doctor may run several tests to see if your symptoms are caused by a heart attack or another form of chest discomfort. If your doctor thinks you're having a heart attack, the first two tests you have are:

Electrocardiogram (ECG). This is the first test done to diagnose a heart attack. It's often done while you're being asked questions about your symptoms. This test records the electrical activity of your heart via electrodes attached to your skin. Impulses are recorded as "waves" displayed on a monitor or printed on paper. Because injured heart muscle doesn't conduct electrical impulses normally, the ECG may show that a heart attack has occurred or is in progress.

Blood tests. Certain heart enzymes slowly leak into your blood if your heart has been damaged by a heart attack. Emergency room staff will take samples of your blood to test for the presence of these enzymes.

Your doctor will look at these test results and determine the seriousness of your condition. If your blood tests show no markers of a heart attack and your chest pain has gone away, you'll likely be given tests to check the blood flow through your heart. If your test results reveal that you've had a heart attack or that you may be at high risk to have a heart attack, you'll likely be admitted to the hospital. You may then have more-invasive tests, such as a coronary angiogram.

Your doctor may also order additional tests, either to figure out if your heart's been damaged by a heart attack, or if your symptoms have been brought on by another cause:

Echocardiogram. If your doctor decides you haven't had a heart attack and your risk of having a heart attack is low, you'll likely have an echocardiogram before you leave the hospital. This test uses sound waves to produce an image of your heart. During an echocardiogram, sound waves are directed at your heart from a transducer, a wand-like device, held on your chest. The sound waves bounce off your heart and are reflected back through your chest wall and processed electronically to provide video images of your heart. An echocardiogram can help identify whether an area of your heart has been damaged by a heart attack and isn't pumping normally.

Chest X-ray. An X-ray image of your chest allows your doctor to check the size and shape of your heart and its blood vessels.

Nuclear scan. This test helps identify blood flow problems to your heart. Small amounts of radioactive material are injected into your bloodstream. Special cameras can detect the radioactive material as it is taken up by your heart muscle. Areas of reduced blood flow to the heart muscle — through which less of the radioactive material flows — appear as dark spots on the scan. Nuclear scans are occasionally done while you're having chest pain to check the blood flow to your heart muscle, but more often, are done as part of a stress test.

Computerized tomography (CT) angiogram. A CT angiogram allows your doctor to check your arteries to see if they're narrowed or blocked. In this minimally invasive test, you'll change into a hospital gown and lie on a table that's part of the CT scanning machine. You'll receive an injection of a radioactive dye, and the doughnut-shaped CT scanner will be moved to take images of the arteries in your heart. The images are then sent to a computer screen for your doctor to view. This test is usually only done if your blood tests and electrocardiogram don't reveal the cause of your symptoms.

Coronary angiogram (cardiac catheterization). This test can show if your coronary arteries are narrowed or blocked. A liquid dye is injected into the arteries of your heart through a long, thin tube (catheter) that's fed through an artery, usually in your leg, to the arteries in your heart. As the dye fills your arteries, the arteries become visible on X-ray, revealing areas of blockage. Additionally, while the catheter is in position, your doctor may treat the blockage by performing an angioplasty. Angioplasty uses tiny balloons threaded through a blood vessel and into a coronary artery to widen the blocked area. Often, a mesh tube (stent) also is placed inside the artery to hold it open more widely and prevent re-narrowing in the future.

Exercise stress test. In the days or weeks following your heart symptoms, you may also undergo a stress test. Stress tests measure how your heart and blood vessels respond to exertion. You may walk on a treadmill or pedal a stationary bike while attached to an ECG machine. Or you may receive a drug intravenously that stimulates your heart in a manner that's similar to the way you heart would be stimulated during exercise. Stress tests help doctors decide the best long-term treatment for you. Your doctor also may order a nuclear stress test, which is similar to an exercise stress test, but uses an injected dye and special imaging techniques to produce detailed images of your heart while you're exercising.

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